Multichannel charge separation induced by multiple internal electric fields in ReS2/CoSx/CdS hollow nanostructures for efficient photocatalysis

Semiconductor junction shows greatly potential in photocatalysis due to the unique merits for charge separation, however the photocatalytic efficiency is still limited by the monotonous charge separation pathway and weak light absorption. Herein, multichannel charge separation driven by multiple internal electric fields (IEFs) has been proposed in ReS 2 /CoS x /CdS hollow nanostructures, which greatly improves the photocatalytic activity. By growing CdS nanoparticles on hollow ReS 2 /CoS x hybrids, the ReS 2 /CoS x /CdS ternary hybrids with Schottky junction (ReS 2 -CoS x ), type-I junction (ReS 2 -CdS), and Ohmic contact (CoS x -CdS) were constructed. The unique hollow structure and bandgap excitation endow the ReS 2 /CoS x /CdS hybrids with high light-harvesting efficiency across a broad spectrum from ultraviolet (UV) to near-infrared (NIR). Ultrafast transient absorption (TA) characterization elucidates the multi-interface charge transfer mechanisms, which involve electron transfer from CoS x to ReS 2 , from CdS to ReS 2 , from CdS to CoS x , and a possible sequential transfer from CdS to CoS x and then to ReS 2 . These pathways significantly prolong the lifetime of charge carriers and suppress charge recombination. Concurrently, the multiple IEFs facilitate charge separation and prevent back-transfer, further inhibiting charge recombination. The ReS 2 /CoS x /CdS hollow nanostructures exhibit remarkably enhanced photocatalytic activity, which is 15.00 and 15.36 times of pure CdS and ReS 2 , respectively, under visible light irradation (λ > 420 nm) with Na 2 S/Na 2 S 2 O 3 as the hole sacrificial agent. This study provides valuable insights for designing efficient photocatalysts based on semiconductor junction, and the synthesized materials show promising potential for solar-driven energy conversion applications.